Load-bearing shaped part and a method for manufacturing shaped parts

#The invention relates to a method for the manufacture of shaped parts. The invention also relates to a load-bearing shaped part.

#Load-bearing shaped parts can be used in various fields of engineering. As an example, various applications in the field of vehicle occupant restraint systems are explained hereinbelow. However, it is expressly pointed out that the invention can be applied to all fields of engineering.

#A shaped part to which the invention can be applied is, for example, a locking catch which can be used to connect a belt tensioner drive with the belt spool of a belt winder. The locking catch is part of a coupling which in normal state separates the belt winder from the belt tensioner drive, so that the belt spool of the belt winder is freely rotatable. If, however, the belt tensioner drive is activated, for example by a sensor arranged on the vehicle, which establishes that given thresholds of the vehicle deceleration have been exceeded, the belt tensioner drive must be coupled with the belt spool within the shortest period of time, in order to provide a rotation of the belt spool in the belt webbing winding direction. Owing to the required short response time and also the moment of rotation which is to be transferred, the locking catch is exposed here to high stresses.

#The invention is described hereinbelow with reference to various embodiments which are illustrated in the enclosed drawings in which:

#FIG. 1 shows a longitudinal section through a profiled piece which can be used in a method according to the invention;

#FIGS. 2 to 5 diagrammatically show four process steps manufacturing a shaped part by a method according to the invention;

#With the aid of FIGS. 1 to 6, the method according to the invention is schematically described. By cutting a profiled material (not shown) of an Aluminum alloy to length, the profiled piece 10 illustrated in FIG. 1 is obtained. The profiled material can be provided, for example, on a supply reel. The respective length of the profiled piece is determined on the basis of the volume of the shaped part which is to be produced, so that the volume of the profiled piece is at least equal to the volume of the shaped part plus the volume decrease of the profiled piece resulting from compacting the material, occurring in the course of the process, which, however, is very small. The profiled material is an Aluminum alloy of strength classifications F17 to F50. Preferably, either the profiled material is soft-annealed before cutting to length or the produced profiled piece 10 is soft-annealed before further processing, so that the cold working of the aluminum alloy occurring in the manufacture of the profiled material is eliminated and a very good formability of the material is produced.

#The profiled piece 10 is then inserted into a press 14, which consists substantially of a die 16 and a punch. In addition, in the interior of the die 16 an ejector 21 is provided which is movable relative thereto. In FIG. 2, it is illustrated how the profiled piece 10 is inserted into the die 16. Then, the punch 18 is introduced into the die 16 until a plunger protrusion 22, the outer diameter of which is slightly smaller than the internal diameter of the blank 10, engages therein.

#As can be seen in FIG. 3, the punch 18 is forced further into the die 16, whereby the profiled piece 10 on the one hand is forced into the die 16 until it lies against the ejector 21, and on the other hand is flared slightly at its opposite axial end by means of a punch cone 24 adjoining the plunger protrusion 24.